Schema Versioning

Change table schemas with zero downtime and roll back to any previous version.

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Overview

Altering schemas on a live database is risky. DBX’s schema versioning keeps a full change history, ensuring safe DDL operations with rollback capability.

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Basic Usage

use dbx_core::engine::schema_versioning::SchemaVersionManager;

let manager = SchemaVersionManager::new();

// Register table (v1)
let v = manager.register_table("users", schema_v1)?;
assert_eq!(v, 1);

// Add column (v2)
let v = manager.alter_table("users", schema_v2, "Add email column")?;
assert_eq!(v, 2);

// Get current schema — O(1) performance (DashMap cache)
let schema = manager.get_current("users")?;

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Version Management

// Check current version
let version = manager.current_version("users")?;  // → 2

// Get schema at a specific version
let old_schema = manager.get_at_version("users", 1)?;

// Roll back to a previous version
manager.rollback("users", 1)?;
let version = manager.current_version("users")?;  // → 1

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Version History

let history = manager.history("users")?;
for entry in &history {
    println!("v{}: {} ({})", entry.version, entry.description, entry.created_at);
}
// Output:
// v1: Initial schema (2026-02-15 11:00)
// v2: Add email column (2026-02-15 14:30)

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Performance

Operation	Time	Note
get_current	46 ns	Direct DashMap cache lookup
alter_table	746 ns	Add new version
8-thread concurrent reads	18.1M ops/s	2.44x faster than RwLock

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Next Steps

• Indexing Guide — Index versioning integration
• Transactions Guide — DDL and transaction interaction